I'm not sure if it's using your environment correctly, or are you expecting ~150 errors? Lots of import errors, and I'm guessing most of the other ones are errors because it couldn't infer what was imported.

how does it compare against mypy? is it much faster?

How does it compare against Pyright. Pyright is the gold standard of Python type checking currently. Mypy is slower and buggier.

I tested it side-by-side on my ~100Kloc codebase.

Ty: 2.5 seconds, 1599 diagnostics, almost all of which are false positives

Pyright: 13.6 seconds, 10 errors, all of which are actually real errors

There's plenty of potential here, but Ty's type inference is just not as sophisticated as Pyright's at this time. That's not surprising given it hasn't even been released yet.

Whether Ty will still perform so much faster once all of Pyright's type inference abilities have been matched or implemented - well, that remains to be seen.

Pyright runs on Node, so I would expect it to be a little slower than Ty, but perhaps not by very much, since modern JS engines are already quite fast and perform within a factor of ~2-3x of Rust. That said, I'm rooting for Ty here, since even a 2-3x performance boost would be useful.

0.2s on ty compared to 4.7s on pyright. Not even close.

Mypy is also able to check things that are inexpressible with stubs, among other things

In the same folder:

    time uvx mypy .    

Result:

    uvx mypy .  0.46s user 0.09s system 74% cpu 0.740 total

So ty is about 7x faster - but remember ty is still in development and may not catch the same errors / report false errors, so it's not a fair comparison yet.

Note that `uvx mypy` may give you inaccurate timings on macOS. The antivirus in macOS goes a little crazy the first time it executes a mypyc compiled program.